Rethreading die



Oct. 3, E R* KOONZ RETHREADING DIE Filed June 4, 1932 f-f En@ SH ma#)JuvcFP-.V den Patented Oct. 3,1933 Y l- I t' n. l Y l 1 UNITED STATESPATENT'0F'Fl-CE*,

RETHREADING DIE Earl R; Koonz, Greenfield, Masts., assignor toGreenfield Tap & Die Corporation, Greenfield, Mass., a corporation ofMassachusetts Y Application June 4, 1932. seria; No. 615,393 zclaims.(C1. 1li- 116) This invention relates to thread cutting dies threadVv isto be re-cut, Ispring they die blocks which are particularly designedfor re-cutting l apart suiciently so that there-threading'die Worn ordamaged screw-threads. K l can be slipped over the damaged end threadslIt is the general object of my invention to and accurately seated on theuninjured threads provide an improved constructionA of re-thread- -awayfrom. theend of the bolt. The spring 22 60 ing die for such purposes, sodesigned that it permits the die blocks to be thus spread apart I may beeasily applied to the work and quickly for application to the bolt butyieldingly holds seated in the original threads. the die blocks l0 inassembled `relation cn the I also provide means to cause the separablebolt while the stock 11 is applied tothe die blocks l0 parts of the dieto yieldingly engage the work 10 and the vscrews 13 are adjusted.tocause the 65 and to retain their position thereon during Ythe die blocksto closely engage the uninjured threads application of a die-stockthereto. on the bolt B. Y

' My invention further relates to arrangements The re-threading dieisthen rotated by .the and combinations of Yparts which will be herestock11 in such a direction as to causethe die Y l5 inafter described andmore particularly pointed to cut toward the end of the bolt, thus avoid-70 out in the'appended claims. l ing the diculty of starting the die onbruised A preferred form of the invention is shown in threads, with theusual result 'of cross-threading.V the drawing, in which The springplate 22 permits a slight relative Fig. l is a plan view of a die-stockcontaining movement of thedie blocks 10 to adjust them'- my improvedre-threading die; selves to the sometimes irregular rscrew-threads 75Fig. 2 is a plan view of the die itself; to which they-are applied. K lFig. 3 is a side elevation, looking in the direc- As the toothedsectionsl5fhave both forward. tion of the arrow 3 in Fig. 2, and and rearwardcutting faces, my improved ref' Fig. lis aplan View, partly in section,and lookthreading die may be used asabove described, ing in thedirection of the arrow 4 in Fig. 2. cutting outward from the inner endof the bolt Y80 Referring to the drawing, my improved rethread, or maybe used by starting at the `end threading die comprises a pair of dieblocks l0 of the bolt and cutting the thread in the usual adapted to beassembled in the usual die holder way. The latter method of operation isprefer- 11 and having peripheral depressions 12to reable when theextreme end threads are unin- So ceive the pointed inner ends ofclamping and juredand the thread .may be' easily caught. S5. adjustingscrews 13. Y Having thus described my inventionand the' The die blocksl0 are provided with Athe usual advantages thereof.' I do not wish tobev limited cutting sections 15, spaced apart by.recesses or to theVdetailsV herein disclosed, otherwise than clearance openings 16. Thecutting sections l5 as set forth in the claims, but what I claim is:-

are preferably provided with both forward, and `1. A ree-threading dielcomprising two die blocks 9o rearward cutting faces and the teeth areformed with flattened end portions, and a light flat Vleaf withoutclearance, so that the die will cut equally spring having lits endssecured to said attened well in either direction. end portionsandfsubstantially within thefpe- 5 A groove or recess 20 is formed inone end ol' riphery of said die blocks. 40 Veach die block 10 and a atspring plate 22 is Y 2. Are-threading die comprising two die blockssecured in the recesses 20 by screws 24. provided with end. grooves,vand a light flat leaf The method of useand the advantages of my springmember secured'in'vsaid end grooves suby improved re-threading die` areclearly disclosed stantially within theperiphery of said die blocks inFig. 4, where the die is shown mountedon` and holdingsaid'die blocksyieldinglyin'assema bolt B having threads which have been bruised bledrelation. 100

in their outer end portion. When such a screw l EARL ARQVKOCirlZ'.V

